Periodic Reporting for period 1 - SMACool (Shape Memory Alloy based elastocaloric Cooling system)
Reporting period: 2024-10-01 to 2025-09-30
The project SMACool will develop a functional air-conditioning device for residential buildings, based on the emerging technology of elastocalorics, which uses (shape memory) alloys as solid-state refrigerants for efficient and sustainable cold (and heat) generation.
Elastocalorics (also thermo-elastic or thermoelastics) is an innovative, disruptive heating and cooling technology with the potential of reaching outstanding energy efficiency and zero global warming potential, using metals as solid-state refrigerant material instead of the harmful fluids used in cooling systems today. The interdisciplinary project consortium consisting of three European Universities from Germany, Italy and Slovenia and one emerging high-tech Company from Ireland, will cover several project objectives, including the construction and validation of an application-specific elastocaloric cooling system device, the creation of a versatile validation environment for quantitative validation of future elastocaloric devices, the realization of a multi-physical numerical simulation platform for simulative assistance in elastocaloric device development, the development and characterization of elastocaloric-specific optimized materials, and the development of an efficient electric drive unit suited for the specific needs of elastocaloric system devices. The resulting SMACool system is targeting an efficiency increase by a factor of two to three compared to state-of-the-art HVAC (Heat, Ventilation, and Air-Conditioning) systems and will have high impact on potentially cutting down global energy consumption in the residential building sector and also other cold generation fields.
Elastocalorics (also thermo-elastic or thermoelastics) is an innovative, disruptive heating and cooling technology with the potential of reaching outstanding energy efficiency and zero global warming potential, using metals as solid-state refrigerant material instead of the harmful fluids used in cooling systems today. The interdisciplinary project consortium consisting of three European Universities from Germany, Italy and Slovenia and one emerging high-tech Company from Ireland, will cover several project objectives, including the construction and validation of an application-specific elastocaloric cooling system device, the creation of a versatile validation environment for quantitative validation of future elastocaloric devices, the realization of a multi-physical numerical simulation platform for simulative assistance in elastocaloric device development, the development and characterization of elastocaloric-specific optimized materials, and the development of an efficient electric drive unit suited for the specific needs of elastocaloric system devices. The resulting SMACool system is targeting an efficiency increase by a factor of two to three compared to state-of-the-art HVAC (Heat, Ventilation, and Air-Conditioning) systems and will have high impact on potentially cutting down global energy consumption in the residential building sector and also other cold generation fields.
The SMACool project consists of nine interconnected work packages (WPs). WP1 addresses project organization, while WP8 and WP9 focus on networking within the portfolio and all communication, dissemination, and exploitation activities. WP2 serves as the scientific starting point and foundation of the project, as all consortium members will develop the system approach, concept, and architecture together. The results from WP2 are then applied in WPs 3, 4, 5, and 6, which cover four different research areas: materials, simulation, drive system development, and system device realization. All four WPs have strong interactions with each other and are supported by WP7, which handles experimental characterization and validation across all project areas and phases.
Initial evaluations of various elastocaloric device concepts were conducted numerically, also as part of WP4. The primary objective was to define operating conditions capable of delivering cooling power of at least 500 W, with a temperature span of 15 K, and a maximized Coefficient of Performance (COP).
Next task was to develop a geometry for a compressively loaded elastocaloric structure (regenerator) that facilitates efficient heat transfer while preventing structural buckling during compression. Preliminary simulations have been conducted to assess the buckling behavior of several targeted designs under compressive loading with promising results, which lead to experimental verification in the next step.
For the solid-state refrigerant material, work has focused on the development of Exergyn’s proprietary NiTi-based shape memory alloy, specifically tailored for elastocaloric operation. Testing shows the material to be structurally and functionally stable, with sharp transformation behavior and low hysteresis under compression. In parallel, a second proprietary melting route is being developed. This aims to reduce the mechanical and thermal stabilization typically needed during early cycling, so the material reaches steady high efficiency performance much faster. The expectation is that this will lower the work input on initial actuation and improve energy efficiency (COP). Internal trials are in progress, with early results showing promise. Material production has been scaled from small laboratory quantities to ingots exceeding 100 g. This provides enough material for detailed testing under realistic load and temperature conditions.
For the drive system, two mechanisms were investigated for converting rotational motion into linear compression for SMA elements, which are currently object of protection measures.
To precisely evaluate system performance, a laboratory testing environment for HVAC devices has been developed and is being realized. This test setup consists of two isolated, temperature-controlled chambers that simulate outdoor (seasonal) and indoor (room with thermal load) air for the device under test. The chamber temperatures are controlled by commercially available, custom-adapted temperature control units. To evaluate the device’s performance, flow rates and temperatures at the inlets and outlets of the chambers are measured to calculate the thermal power. Additional measurement of the device’s electrical power consumption enables calculation of the Seasonal Coefficient of Performance (SCOP).
Initial evaluations of various elastocaloric device concepts were conducted numerically, also as part of WP4. The primary objective was to define operating conditions capable of delivering cooling power of at least 500 W, with a temperature span of 15 K, and a maximized Coefficient of Performance (COP).
Next task was to develop a geometry for a compressively loaded elastocaloric structure (regenerator) that facilitates efficient heat transfer while preventing structural buckling during compression. Preliminary simulations have been conducted to assess the buckling behavior of several targeted designs under compressive loading with promising results, which lead to experimental verification in the next step.
For the solid-state refrigerant material, work has focused on the development of Exergyn’s proprietary NiTi-based shape memory alloy, specifically tailored for elastocaloric operation. Testing shows the material to be structurally and functionally stable, with sharp transformation behavior and low hysteresis under compression. In parallel, a second proprietary melting route is being developed. This aims to reduce the mechanical and thermal stabilization typically needed during early cycling, so the material reaches steady high efficiency performance much faster. The expectation is that this will lower the work input on initial actuation and improve energy efficiency (COP). Internal trials are in progress, with early results showing promise. Material production has been scaled from small laboratory quantities to ingots exceeding 100 g. This provides enough material for detailed testing under realistic load and temperature conditions.
For the drive system, two mechanisms were investigated for converting rotational motion into linear compression for SMA elements, which are currently object of protection measures.
To precisely evaluate system performance, a laboratory testing environment for HVAC devices has been developed and is being realized. This test setup consists of two isolated, temperature-controlled chambers that simulate outdoor (seasonal) and indoor (room with thermal load) air for the device under test. The chamber temperatures are controlled by commercially available, custom-adapted temperature control units. To evaluate the device’s performance, flow rates and temperatures at the inlets and outlets of the chambers are measured to calculate the thermal power. Additional measurement of the device’s electrical power consumption enables calculation of the Seasonal Coefficient of Performance (SCOP).
After 12 months in the project, several results beyond the current state of the art have been generated:
1.) An innovative system architecture has been designed, which will provide the needed cooling power and beat today's efficiency (COP) values of competing technologies. The designs are based on calcualtions and simulations and need to be verified experimentally in the upcoming project phase.
2.) New elastocaloric materials and their according processing have been developed, which beat the perfomance of materials available today.
3.) New drive system approaches, which further enhance a maximum efficient system operation, are in development for this specific application.
1.) An innovative system architecture has been designed, which will provide the needed cooling power and beat today's efficiency (COP) values of competing technologies. The designs are based on calcualtions and simulations and need to be verified experimentally in the upcoming project phase.
2.) New elastocaloric materials and their according processing have been developed, which beat the perfomance of materials available today.
3.) New drive system approaches, which further enhance a maximum efficient system operation, are in development for this specific application.